Washington -LRB- CNN -RRB- -- Baseball all-time home run champion Barry Bonds won a big legal victory Friday when a federal appeals court ruled that evidence the government says would prove he lied about using steroids is inadmissible in court .

The San Francisco-based 9th Circuit U.S. Court of Appeals , in a divided opinion , said the government can not use urine samples and other evidence in its perjury case against the former San Francisco Giants star .

Bonds was indicted in federal court in December 2008 on 10 counts of making false statements to a grand jury -- specifically , denying that he knowingly took steroids and other performance-enhancing drugs .

His criminal trial has been delayed while the legal issues are being worked out . It was unclear whether the Justice Department will now appeal to the Supreme Court in an effort to allow the evidence to be used in court .

The Appeals Court ruling upholds a February 2009 ruling from U.S. District Judge Susan Illston that there was no proof that positive steroid tests from 2000 and 2001 were Bonds ' and that out-of-court statements from his former trainer , Greg Anderson , are hearsay .

The appeals court majority said the repeated refusal of Anderson to testify against Bonds means evidence allegedly gathered by him is considered `` inadmissible , since he would be unable to vouch for its authenticity . ''

Robert Talbot , a professor at the University of San Francisco School of Law said the ruling essentially torpedoes the prosecution 's case , which was heavily dependent on evidence and information from Bonds ' former trainer .

`` There was a link missing here , that the only way to get down to the nitty-gritty that this was from Barry Bonds was using hearsay testimony , '' Talbot said .

Anderson , he said , `` had possession of the evidence and he had that knowledge , and you ca n't use that knowledge unless he actually testifies under oath . ''

`` To try and prove the case beyond a reasonable doubt , particularly in San Francisco where there are going to be many , many people chosen for a jury who would be behind Barry Bonds -- it should be the death knell , '' Talbot said .

`` Practically speaking they should say , ` We gave it our best shot , and it 's just not there , ' '' he said .

Anderson allegedly took urine samples and delivered them to a Bay-area lab known as BALCO . At issue in the appeal was whether the tested samples actually came from Bonds , and Anderson 's employment status at the time .

The appeals court concluded Anderson was an `` independent contractor '' -- not directly hired by Bonds . Because Bonds also did not control the samples , the court reasoned , Anderson would need to testify in person on the material and the chain of possession .

The government said it would instead bring BALCO executive James Valente to the stand to testify Anderson told him the samples indeed came from Bonds .

The court ultimately agreed with the arguments presented by Bonds ' lawyers . `` Because the government was attempting to use Anderson 's out-of-court statements to prove the truth of what they contained , Bonds argued that Anderson 's statements were inadmissible hearsay and that the lab results could not be authenticated as Bonds ' in that manner . ''

Bonds hit a record-setting 73 homers in the 2001 season . That same year , as well as before and after , the FBI said BALCO Laboratories recorded urine and blood tests , under the name `` Barry Bonds , '' showing `` positive '' results for steroids and performance-enchancing drugs .

The government had the burden of showing the samples came from Bonds , then went to Anderson and then to BALCO . Anderson has refused to testify and has been jailed for contempt of court on several occasions .

`` There must be at least some manifestation of assent to the principal 's right to control , '' said the court of Bonds . `` Here , the testing was performed on Anderson 's own initiative and not at the request of Bonds . The dissent incorrectly assumes otherwise . Thus , the district court did not abuse its discretion in finding that Anderson was not an agent for the limited purpose of the drug testing . ''

The government alleges BALCO helped supply Bonds with steroids and drug-masking substances . BALCO was accused of covertly marketing tetrahydrogestrinone -- known as `` the Clear '' -- a then-undetectable performance-enhancing steroid .

Company founder Victor Conte and associates such as Anderson allegedly supplied other top athletes with the Clear and human growth hormone , assuring the competitors they would not be caught cheating . The lab performed repeated tests on athletes , said the government , to check whether the drugs were detectable . Top professional football and track stars were caught up in the scandal , prosecutors say .

Steroid use was banned by Major League Baseball in 2003 .

Neither the government nor Bonds had an immediate reaction to the ruling . In light of the decision , it remains unclear whether the criminal trail will proceed .

The case is U.S. v. Bonds -LRB- 09-10079 -RRB- .

CNN 's Augie Martin and Matt Cherry contributed to this report .

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NEW : Law professor : `` It should be the death knell '' for prosecution

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Appeals Court says there is no proof that the steroid tests were from Bonds

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Former trainer , who reportedly said samples came from Bonds , refuses to testify

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No word yet on further appeal